windows-server-2003/base/mvdm/v86/monitor/i386/monitor.c

/*++

Copyright (c) 1990  Microsoft Corporation

Module Name:

    Monitor.c
Abstract:

    This module is the user mode portion of the x86 monitor

Author:

    Dave Hastings (daveh) 16 Mar 1991

Environment:

    User mode only

Revision History:
    Sudeep Bharati (sudeepb) 31-Dec-1991

    Converted all register manipulation interfaces to functions
    from macros. This is to make ntvdm an exe as well as a dll,
    and these register oriented routines are exported from ntvdm
    for WOW32 and other installable VDDs.

    Dave Hastings (daveh) 18-Apr-1992

    Split into multiple files. Track current monitor thread by
    Teb pointer.  Register initial thread.

    Sudeep Bharati (sudeepb) 22-Sep-1992

    Added Page Fault Handling For installable VDD support

--*/


#include "monitorp.h"
#include "dbgsvc.h"

//
// Internal functions
//

VOID
EventVdmIo(
    VOID
    );

VOID
EventVdmStringIo(
    VOID
    );

VOID
EventVdmMemAccess(
    VOID
    );

VOID
EventVdmIntAck(
    VOID
    );

VOID
EventVdmBop(
    VOID
    );

VOID
EventVdmError(
    VOID
    );

VOID
EventVdmIrq13(
    VOID
    );

VOID
EventVdmHandShakeAck(
    VOID
    );

VOID
CreateProfile(
    VOID
    );

VOID
StartProfile(
    VOID
    );

VOID
StopProfile(
    VOID
    );

VOID
AnalyzeProfile(
    VOID
    );

VOID
CheckScreenSwitchRequest(
    HANDLE handle
    );

// [LATER]  how do you prevent a struct from straddling a page boundary?

ULONG   IntelBase;          // base memory address
ULONG   VdmSize;            // Size of memory in VDM
ULONG   VdmDebugLevel;      // used to control debugging
PVOID  CurrentMonitorTeb;   // thread that is currently executing instructions.
ULONG InitialBreakpoint = FALSE; // if set, breakpoint at end of cpu_init
ULONG InitialVdmTibFlags = INITIAL_VDM_TIB_FLAGS; // VdmTib flags picked up from here
CONTEXT InitialContext;     // Initial context for all threads
BOOLEAN DebugContextActive = FALSE;
ULONG VdmFeatureBits = 0;   // bit to indicate special features
BOOLEAN MainThreadInMonitor = TRUE;

extern PVOID NTVDMpLockPrefixTable;
extern BOOL  HandshakeInProgress;
extern HANDLE hSuspend;
extern HANDLE hResume;
extern HANDLE hMainThreadSuspended;

extern PVOID __safe_se_handler_table[]; /* base of safe handler entry table */
extern BYTE  __safe_se_handler_count;   /* absolute symbol whose address is
                                           the count of table entries */

IMAGE_LOAD_CONFIG_DIRECTORY _load_config_used = {
    sizeof(_load_config_used),                          // Reserved
    0,                          // Reserved
    0,                          // Reserved
    0,                          // Reserved
    0,                          // GlobalFlagsClear
    0,                          // GlobalFlagsSet
    0,                          // CriticalSectionTimeout (milliseconds)
    0,                          // DeCommitFreeBlockThreshold
    0,                          // DeCommitTotalFreeThreshold
    (ULONG)&NTVDMpLockPrefixTable,     // LockPrefixTable, defined in FASTPM.ASM
    0, 0, 0, 0, 0, 0, 0,        // Reserved
    0,                             // & security_cookie
    (ULONG)__safe_se_handler_table,
    (ULONG)&__safe_se_handler_count
};

// Bop dispatch table

extern void (*BIOS[])();

//
// Event Dispatch table
//

VOID (*EventDispatch[VdmMaxEvent])(VOID) = {
        EventVdmIo,
        EventVdmStringIo,
        EventVdmMemAccess,
        EventVdmIntAck,
        EventVdmBop,
        EventVdmError,
        EventVdmIrq13,
        EventVdmHandShakeAck
        };

#if DBG
BOOLEAN fBreakInDebugger = FALSE;
#endif



EXPORT
VOID
cpu_init(
    )

/*++

Routine Description:

    This routine is used to prepare the IEU for instruction simulation.
    It will set the Intel registers to thier initial value, and perform
    any implementation specific initialization necessary.


Arguments:


Return Value:

    None.

--*/

{
    NTSTATUS Status;

    InitialVdmTibFlags |= RM_BIT_MASK;


    //
    // Find out if we are running with IOPL.  We call the kernel
    // rather than checking the registry ourselves, so that we can
    // insure that both the kernel and ntvdm.exe agree.  If they didn't,
    // it would result in unnecssary trapping instructions.  Whether or
    // not Vdms run with IOPL only changes on reboot
    //
    Status = NtVdmControl(VdmFeatures, &VdmFeatureBits);

#if DBG
    if (!NT_SUCCESS(Status)) {
        DbgPrint(
            "NTVDM: Could not find out whether to use IOPL, %lx\n",
            Status
            );
    }
#endif

    //
    // If we have fast v86 mode IF emulation set the bit that tells
    // the 16 bit IF macros they know.
    //
    if (VdmFeatureBits & V86_VIRTUAL_INT_EXTENSIONS) {
        InitialVdmTibFlags |= RI_BIT_MASK;
    }

    *pNtVDMState = InitialVdmTibFlags;

    // Switch the npx back to 80 bit mode.  Win32 apps start with
    // 64-bit precision for compatibility across platforms, but
    // DOS and Win16 apps expect 80 bit precision.
    //

    _asm fninit;

    //
    // We setup the InitialContext structure with the correct floating
    // point and debug register configuration, and cpu_createthread
    // uses this context to configure each 16-bit thread's floating
    // point and debug registers.
    //

    InitialContext.ContextFlags = CONTEXT_FLOATING_POINT | CONTEXT_DEBUG_REGISTERS;

    Status = NtGetContextThread(
        NtCurrentThread(),
        &InitialContext
        );

    if (!NT_SUCCESS(Status)) {
#if DBG
        DbgPrint("NtVdm terminating : Could not get float/debug context for\n"
                 "                    initial thread, status %lx\n", Status);
        DbgBreakPoint();
#endif
        TerminateVDM();
    }


    //
    //
    // Turn OFF em bit so that dos apps will work correctly.
    //
    // On machines without 387's the floating point flag will have been
    // cleared.
    //

    InitialContext.ContextFlags = CONTEXT_FLOATING_POINT;
    InitialContext.FloatSave.Cr0NpxState &= ~0x6; // CR0_EM | CR0_MP

    //
    // Do the rest of thread initialization
    //
    cpu_createthread( NtCurrentThread(), NULL );

    InterruptInit();

    if (InitialBreakpoint) {
        DbgBreakPoint();
    }

}

EXPORT
VOID
cpu_terminate(
    )
/*++

Routine Description:


Arguments:


Return Value:


--*/
{
    InterruptTerminate();
}

EXPORT
VOID
cpu_simulate(
    )

/*++

Routine Description:

    This routine causes the simulation of intel instructions to start.

Arguments:

Return Value:

    None.

--*/

{
    NTSTATUS Status;
    PVDM_TIB VdmTib;
    ULONG oldIntState = VDM_VIRTUAL_INTERRUPTS;

    DBGTRACE(VDMTR_TYPE_MONITOR | MONITOR_CPU_SIMULATE, 0, 0);

    CurrentMonitorTeb = NtCurrentTeb();
    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;

    VdmTib->ContinueExecution = TRUE;


    VdmTib->VdmContext.ContextFlags = CONTEXT_FULL;

    while (VdmTib->ContinueExecution) {

        //ASSERT(CurrentMonitorTeb == NtCurrentTeb());
        ASSERT(InterlockedIncrement(&VdmTib->NumTasks) == 0);

        if (*pNtVDMState & VDM_INTERRUPT_PENDING) {
            DispatchInterrupts();
        }

        // translate MSW bits into EFLAGS
        if ( getMSW() & MSW_PE ) {
            if (!VDMForWOW && !getIF() && oldIntState == VDM_VIRTUAL_INTERRUPTS) {

                //
                // For PM apps, we need to set Cli time stamp if interrupts
                // are disabled and the time stamp was not set already.
                // This is because apps may use int31 to change interrupt
                // state instead of using cli.
                //

                VDM_PM_CLI_DATA cliData;

                cliData.Control = PM_CLI_CONTROL_SET;
                NtVdmControl(VdmPMCliControl, &cliData);
            }

            VdmTib->VdmContext.EFlags &= ~EFLAGS_V86_MASK;
            if (HandshakeInProgress) {
                CheckScreenSwitchRequest(hMainThreadSuspended);
            }
            MainThreadInMonitor = FALSE;

            Status = FastEnterPm();
        } else {
            VdmTib->VdmContext.EFlags |= EFLAGS_V86_MASK;
            if (HandshakeInProgress) {
                CheckScreenSwitchRequest(hMainThreadSuspended);
            }
            MainThreadInMonitor = FALSE;

            Status = NtVdmControl(VdmStartExecution,NULL);
        }

        MainThreadInMonitor = TRUE;
        if (HandshakeInProgress) {
            CheckScreenSwitchRequest(hMainThreadSuspended);
        }
        if (!NT_SUCCESS(Status)) {
#if DBG
            DbgPrint("NTVDM: Could not start execution\n");
#endif
            return;
        }

        //
        // Refresh VdmTib for the fact that wow32 thread never enters cpu_simulate
        // but returns here to handle BOP
        // Note, I think this needs only in FREE build.
        //

        CurrentMonitorTeb = NtCurrentTeb();
        VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
        if (!VDMForWOW) {
            oldIntState = getIF() ? VDM_VIRTUAL_INTERRUPTS : 0;
        }

        ASSERT(InterlockedDecrement(&VdmTib->NumTasks) < 0);

#if DBG
        if (fBreakInDebugger) {
            fBreakInDebugger = 0;
            DbgBreakPoint();
        }
#endif

        // Translate Eflags value
        ASSERT ((!((VdmTib->VdmContext.EFlags & EFLAGS_V86_MASK) &&
            (getMSW() & MSW_PE))));

        if ( VdmTib->VdmContext.EFlags & EFLAGS_V86_MASK ) {
            VdmTib->VdmContext.EFlags &= ~EFLAGS_V86_MASK;
        }

        // bugbug does cs:eip wrap cause some kind of fault?
        VdmTib->VdmContext.Eip += VdmTib->EventInfo.InstructionSize;

        if (VdmTib->EventInfo.Event >= VdmMaxEvent) {
#if DBG
            DbgPrint("NTVDM: Unknown event type\n");
            DbgBreakPoint();
#endif
            VdmTib->ContinueExecution = FALSE;
            continue;
        }
        (*EventDispatch[VdmTib->EventInfo.Event])();
    }


    // set this back to true incase we are nested
    VdmTib->ContinueExecution = TRUE;

    //
    // Restore the old Vdm tib info.  This is necessary for the for the
    // case where the application thread is suspended, and a host simulate is
    // performed from another thread
    //

    DBGTRACE(VDMTR_TYPE_MONITOR | MONITOR_CPU_UNSIMULATE, 0, 0);
}

VOID
host_unsimulate(
    )

/*++

Routine Description:

    This routine causes execution of instructions in a VDM to stop.

Arguments:


Return Value:

    None.

--*/

{
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->ContinueExecution = FALSE;

}


VOID
EventVdmIo(
    VOID
    )
/*++

Routine Description:

    This function calls the appropriate io simulation routine.

Arguments:


Return Value:

    None.

--*/
{
    PVDM_TIB VdmTib;

    EnableScreenSwitch(TRUE, hMainThreadSuspended);   // only in FULLSCREEN
    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    if (VdmTib->EventInfo.IoInfo.Size == 1) {
        if (VdmTib->EventInfo.IoInfo.Read) {
            inb(VdmTib->EventInfo.IoInfo.PortNumber,(half_word *)&(VdmTib->VdmContext.Eax));
        } else {
            outb(VdmTib->EventInfo.IoInfo.PortNumber,getAL());
        }
    } else if (VdmTib->EventInfo.IoInfo.Size == 2) {
        if (VdmTib->EventInfo.IoInfo.Read) {
            inw(VdmTib->EventInfo.IoInfo.PortNumber,(word *)&(VdmTib->VdmContext.Eax));
        } else {
            outw(VdmTib->EventInfo.IoInfo.PortNumber,getAX());
        }
    }
#if DBG
    else {
    DbgPrint(
        "NtVdm: Unimplemented IO size %d\n",
        VdmTib->EventInfo.IoInfo.Size
        );
    DbgBreakPoint();
    }
#endif
    DisableScreenSwitch(hMainThreadSuspended);
}

VOID
EventVdmStringIo(
    VOID
    )
/*++

Routine Description:

    This function calls the appropriate io simulation routine.

Arguments:


Return Value:

    None.

--*/
{
   PVDMSTRINGIOINFO pvsio;
   PUSHORT pIndexRegister;
   USHORT Index;
   PVDM_TIB VdmTib;

   EnableScreenSwitch(TRUE, hMainThreadSuspended);
   VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;

   // WARNING no 32 bit address support

    pvsio = &VdmTib->EventInfo.StringIoInfo;

    if (pvsio->Size == 1) {
        if (pvsio->Read) {
            insb((io_addr)pvsio->PortNumber,
                 (half_word *)Sim32GetVDMPointer(pvsio->Address, 1, ISPESET),
                 (word)pvsio->Count
                 );
            pIndexRegister = (PUSHORT)&VdmTib->VdmContext.Edi;
        } else {
            outsb((io_addr)pvsio->PortNumber,
                 (half_word *)Sim32GetVDMPointer(pvsio->Address,1,ISPESET),
                 (word)pvsio->Count
                 );
            pIndexRegister = (PUSHORT)&VdmTib->VdmContext.Esi;
        }
    } else if (pvsio->Size == 2) {
        if (pvsio->Read) {
            insw((io_addr)pvsio->PortNumber,
                 (word *)Sim32GetVDMPointer(pvsio->Address,1,ISPESET),
                 (word)pvsio->Count
                 );
            pIndexRegister = (PUSHORT)&VdmTib->VdmContext.Edi;
        } else {
            outsw((io_addr)pvsio->PortNumber,
                 (word *)Sim32GetVDMPointer(pvsio->Address,1,ISPESET),
                 (word)pvsio->Count
                 );
            pIndexRegister = (PUSHORT)&VdmTib->VdmContext.Esi;
        }
    } else {
#if DBG
         DbgPrint(
             "NtVdm: Unimplemented IO size %d\n",
             VdmTib->EventInfo.IoInfo.Size
             );
         DbgBreakPoint();
#endif
        DisableScreenSwitch(hMainThreadSuspended);
        return;
    }

    if (getDF()) {
        Index = *pIndexRegister - (USHORT)(pvsio->Count * pvsio->Size);
        }
    else {
        Index = *pIndexRegister + (USHORT)(pvsio->Count * pvsio->Size);
        }

    *pIndexRegister = Index;

    if (pvsio->Rep) {
        (USHORT)VdmTib->VdmContext.Ecx = 0;
        }

    DisableScreenSwitch(hMainThreadSuspended);
}

VOID
EventVdmIntAck(
    VOID
    )
/*++

Routine Description:

    This routine is called each time we have returned to monitor context
    to dispatch interrupts. Its function is to check for AutoEoi and call
    the ica to do a nonspecific eoi, when the ica adapter is in AEOI mode.

Arguments:


Return Value:

    None.

--*/
{
    int line;
    int adapter;
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;

    if (VdmTib->EventInfo.IntAckInfo) {
        if (VdmTib->EventInfo.IntAckInfo & VDMINTACK_SLAVE)
            adapter = 1;
        else
            adapter = 0;
        line = -1;

        host_ica_lock();
        ica_eoi(adapter,
                &line,
                (int)(VdmTib->EventInfo.IntAckInfo & VDMINTACK_RAEOIMASK)
                );
        host_ica_unlock();
        }
}


VOID
EventVdmBop(
    VOID
    )
/*++

Routine Description:

    This routine dispatches to the appropriate bop handler

Arguments:


Return Value:

    None.

--*/
{
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    if (VdmTib->EventInfo.BopNumber > MAX_BOP) {
#if DBG
        DbgPrint(
            "NtVdm: Invalid BOP %lx\n",
            VdmTib->EventInfo.BopNumber
            );
#endif
         VdmTib->ContinueExecution = FALSE;
    } else {

       DBGTRACE(VDMTR_TYPE_MONITOR | MONITOR_EVENT_BOP,
                (USHORT)VdmTib->EventInfo.BopNumber,
                (ULONG)(*((UCHAR *)Sim32GetVDMPointer(
                                   (VdmTib->VdmContext.SegCs << 16) | VdmTib->VdmContext.Eip,
                                   1,
                                   ISPESET)))
                );

       (*BIOS[VdmTib->EventInfo.BopNumber])();
       CurrentMonitorTeb = NtCurrentTeb();
   }
}

VOID
EventVdmError(
    VOID
    )
/*++

Routine Description:

    This routine prints a message(debug only), and exits the vdm

Arguments:


Return Value:

    None.

--*/
{
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
#if DBG
    DbgPrint(
        "NtVdm: Error code %lx\n",
        VdmTib->EventInfo.ErrorStatus
        );
    DbgBreakPoint();
#endif
    TerminateVDM();
    VdmTib->ContinueExecution = FALSE;
}

VOID
EventVdmIrq13(
    VOID
    )
/*++

Routine Description:

    This routine simulates an IRQ 13 to the vdm

Arguments:


Return Value:

    None.

--*/
{
    if (!IRQ13BeingHandled) {
        IRQ13BeingHandled = TRUE;
        ica_hw_interrupt(
            ICA_SLAVE,
            5,
            1
            );
    }
}

VOID
EventVdmHandShakeAck(
    VOID
    )
/*++

Routine Description:

    This routine does nothing.

Arguments:


Return Value:

    None.

--*/
{
}

VOID
EventVdmMemAccess(
    VOID
    )
/*++

Routine Description:

    This routine will call the page fault handler routine which
    is common to both x86 and mips.

Arguments:


Return Value:

    None.

--*/
{

    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;

    // RWMode is 0 if read fault or 1 if write fault.

    DispatchPageFault(
        VdmTib->EventInfo.FaultInfo.FaultAddr,
        VdmTib->EventInfo.FaultInfo.RWMode
        );
    CurrentMonitorTeb = NtCurrentTeb();
}


// Get and Set routines for intel registers.

ULONG  getEAX (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  (VdmTib->VdmContext.Eax);
}
USHORT getAX  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)(VdmTib->VdmContext.Eax));
}
UCHAR  getAL  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((BYTE)(VdmTib->VdmContext.Eax));
}
UCHAR  getAH  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((BYTE)(VdmTib->VdmContext.Eax >> 8));
}
ULONG  getEBX (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  (VdmTib->VdmContext.Ebx);
}
USHORT getBX  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)(VdmTib->VdmContext.Ebx));
}
UCHAR  getBL  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((BYTE)(VdmTib->VdmContext.Ebx));
}
UCHAR  getBH  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((BYTE)(VdmTib->VdmContext.Ebx >> 8));
}
ULONG  getECX (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  (VdmTib->VdmContext.Ecx);
}
USHORT getCX  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)(VdmTib->VdmContext.Ecx));
}
UCHAR  getCL  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((BYTE)(VdmTib->VdmContext.Ecx));
}
UCHAR  getCH  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((BYTE)(VdmTib->VdmContext.Ecx >> 8));
}
ULONG  getEDX (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  (VdmTib->VdmContext.Edx);
}
USHORT getDX  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)(VdmTib->VdmContext.Edx));
}
UCHAR  getDL  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((BYTE)(VdmTib->VdmContext.Edx));
}
UCHAR  getDH  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((BYTE)(VdmTib->VdmContext.Edx >> 8));
}
ULONG  getESP (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  (VdmTib->VdmContext.Esp);
}
USHORT getSP  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)VdmTib->VdmContext.Esp);
}
ULONG  getEBP (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  (VdmTib->VdmContext.Ebp);
}
USHORT getBP  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)VdmTib->VdmContext.Ebp);
}
ULONG  getESI (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  (VdmTib->VdmContext.Esi);
}
USHORT getSI  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)VdmTib->VdmContext.Esi);
}
ULONG  getEDI (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  (VdmTib->VdmContext.Edi);
}
USHORT getDI  (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)VdmTib->VdmContext.Edi);
}
ULONG  getEIP (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  (VdmTib->VdmContext.Eip);
}
USHORT getIP (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)VdmTib->VdmContext.Eip);
}
USHORT getCS (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)VdmTib->VdmContext.SegCs);
}
USHORT getSS (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)VdmTib->VdmContext.SegSs);
}
USHORT getDS (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)VdmTib->VdmContext.SegDs);
}
USHORT getES (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)VdmTib->VdmContext.SegEs);
}
USHORT getFS (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)VdmTib->VdmContext.SegFs);
}
USHORT getGS (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)VdmTib->VdmContext.SegGs);
}
ULONG  getCF (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((VdmTib->VdmContext.EFlags & FLG_CARRY) ? 1 : 0);
}
ULONG  getPF (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((VdmTib->VdmContext.EFlags & FLG_PARITY) ? 1 : 0);
}
ULONG  getAF (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((VdmTib->VdmContext.EFlags & FLG_AUXILIARY) ? 1 : 0);
}
ULONG  getZF (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((VdmTib->VdmContext.EFlags & FLG_ZERO) ? 1 : 0);
}
ULONG  getSF (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((VdmTib->VdmContext.EFlags & FLG_SIGN) ? 1 : 0);
}
ULONG  getTF (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((VdmTib->VdmContext.EFlags & FLG_TRAP) ? 1 : 0);
}
ULONG  getIF (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((VdmTib->VdmContext.EFlags & FLG_INTERRUPT) ? 1 : 0);
}
ULONG  getDF (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((VdmTib->VdmContext.EFlags & FLG_DIRECTION) ? 1 : 0);
}
ULONG  getOF (VOID)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((VdmTib->VdmContext.EFlags & FLG_OVERFLOW) ? 1 : 0);
}
USHORT getMSW (VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return  ((USHORT)VdmTib->IntelMSW);
}
USHORT getSTATUS(VOID){
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return (USHORT)VdmTib->VdmContext.EFlags;
}
ULONG  getEFLAGS(VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return VdmTib->VdmContext.EFlags;
}
USHORT getFLAGS(VOID) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return (USHORT)VdmTib->VdmContext.EFlags;
}

VOID setEAX (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Eax = val;
}

VOID setAX  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Eax = (VdmTib->VdmContext.Eax & 0xFFFF0000) |
                            ((ULONG)val & 0x0000FFFF);
}

VOID setAH  (UCHAR val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Eax = (VdmTib->VdmContext.Eax & 0xFFFF00FF) |
                            ((ULONG)(val << 8) & 0x0000FF00);
}

VOID setAL  (UCHAR val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Eax = (VdmTib->VdmContext.Eax & 0xFFFFFF00) |
                            ((ULONG)val & 0x000000FF);
}

VOID setEBX (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Ebx = val ;
}

VOID setBX  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Ebx = (VdmTib->VdmContext.Ebx & 0xFFFF0000) |
                            ((ULONG)val & 0x0000FFFF);
}

VOID setBH  (UCHAR val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Ebx = (VdmTib->VdmContext.Ebx & 0xFFFF00FF) |
                            ((ULONG)(val << 8) & 0x0000FF00);
}

VOID setBL  (UCHAR  val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Ebx = (VdmTib->VdmContext.Ebx & 0xFFFFFF00) |
                            ((ULONG)val & 0x000000FF);
}

VOID setECX (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Ecx = val ;
}

VOID setCX  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Ecx = (VdmTib->VdmContext.Ecx & 0xFFFF0000) |
                            ((ULONG)val & 0x0000FFFF);
}

VOID setCH  (UCHAR val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Ecx = (VdmTib->VdmContext.Ecx & 0xFFFF00FF) |
                            ((ULONG)(val << 8) & 0x0000FF00);
}

VOID setCL  (UCHAR val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Ecx = (VdmTib->VdmContext.Ecx & 0xFFFFFF00) |
                            ((ULONG)val & 0x000000FF);
}

VOID setEDX (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Edx = val ;
}

VOID setDX  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Edx = (VdmTib->VdmContext.Edx & 0xFFFF0000) |
                            ((ULONG)val & 0x0000FFFF);
}

VOID setDH  (UCHAR val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Edx = (VdmTib->VdmContext.Edx & 0xFFFF00FF) |
                            ((ULONG)(val << 8) & 0x0000FF00);
}

VOID setDL  (UCHAR val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Edx = (VdmTib->VdmContext.Edx & 0xFFFFFF00) |
                                ((ULONG)val & 0x000000FF);
}

VOID setESP (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Esp = val ;
}

VOID setSP  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Esp = (VdmTib->VdmContext.Esp & 0xFFFF0000) |
                                ((ULONG)val & 0x0000FFFF);
}

VOID setEBP (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Ebp = val;
}

VOID setBP  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Ebp = (VdmTib->VdmContext.Ebp & 0xFFFF0000) |
                                ((ULONG)val & 0x0000FFFF);
}

VOID setESI (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Esi = val ;
}

VOID setSI  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Esi = (VdmTib->VdmContext.Esi & 0xFFFF0000) |
                                ((ULONG)val & 0x0000FFFF);
}
VOID setEDI (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Edi = val ;
}

VOID setDI  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Edi = (VdmTib->VdmContext.Edi & 0xFFFF0000) |
                                ((ULONG)val & 0x0000FFFF);
}

VOID setEIP (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Eip = val ;
}

VOID setIP  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.Eip = (VdmTib->VdmContext.Eip & 0xFFFF0000) |
                                ((ULONG)val & 0x0000FFFF);
}

VOID setCS  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.SegCs = (ULONG) val & 0x0000FFFF ;
}

VOID setSS  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.SegSs = (ULONG) val & 0x0000FFFF ;
}

VOID setDS  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.SegDs = (ULONG) val & 0x0000FFFF ;
}

VOID setES  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.SegEs = (ULONG) val & 0x0000FFFF ;
}

VOID setFS  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.SegFs = (ULONG) val & 0x0000FFFF ;
}

VOID setGS  (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.SegGs = (ULONG) val & 0x0000FFFF ;
}

VOID setCF  (ULONG val)  {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.EFlags = (VdmTib->VdmContext.EFlags & ~FLG_CARRY) |
                                (((ULONG)val << FLG_CARRY_BIT) & FLG_CARRY);
}

VOID setPF  (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.EFlags = (VdmTib->VdmContext.EFlags & ~FLG_PARITY) |
                                (((ULONG)val << FLG_PARITY_BIT) & FLG_PARITY);
}

VOID setAF  (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.EFlags = (VdmTib->VdmContext.EFlags & ~FLG_AUXILIARY) |
                                (((ULONG)val << FLG_AUXILIARY_BIT) & FLG_AUXILIARY);
}

VOID setZF  (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.EFlags = (VdmTib->VdmContext.EFlags & ~FLG_ZERO) |
                                (((ULONG)val << FLG_ZERO_BIT) & FLG_ZERO);
}

VOID setSF  (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.EFlags = (VdmTib->VdmContext.EFlags & ~FLG_SIGN) |
                                (((ULONG)val << FLG_SIGN_BIT) & FLG_SIGN);
}

VOID setIF  (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.EFlags = (VdmTib->VdmContext.EFlags & ~FLG_INTERRUPT) |
                                (((ULONG)val << FLG_INTERRUPT_BIT) & FLG_INTERRUPT);
}

VOID setDF  (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.EFlags = (VdmTib->VdmContext.EFlags & ~FLG_DIRECTION) |
                                (((ULONG)val << FLG_DIRECTION_BIT) & FLG_DIRECTION);
}

VOID setOF  (ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.EFlags = (VdmTib->VdmContext.EFlags & ~FLG_OVERFLOW) |
                                (((ULONG)val << FLG_OVERFLOW_BIT) & FLG_OVERFLOW);
}

VOID setMSW (USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->IntelMSW = val ;
}

VOID setSTATUS(USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.EFlags = (VdmTib->VdmContext.EFlags & 0xFFFF0000) | val;
}

VOID setEFLAGS(ULONG val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.EFlags = val;
}

VOID setFLAGS(USHORT val) {
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    VdmTib->VdmContext.EFlags = (VdmTib->VdmContext.EFlags & 0xFFFF0000) | val;
}
//
// The following is a private register function
//

ULONG getPE(){
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return((VdmTib->IntelMSW & MSW_PE) ? 1 : 0);
}


PX86CONTEXT
getIntelRegistersPointer(
    VOID
    )
/*++

Routine Description:

    Return Address on Intel Registers for WOW Fast Access

Arguments:

    None

Return Value:

    Pointer to Intel Registers x86 Context Record


--*/
{
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    return &(VdmTib->VdmContext);
}



BOOLEAN MonitorInitializePrinterInfo(
     WORD   Ports,
     PWORD  PortTable,
     PUCHAR State,
     PUCHAR Control,
     PUCHAR Status,
     PUCHAR HostState)
{
    UCHAR   adapter;
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;

    ASSERT (Ports == 3);
    ASSERT (Status != NULL);

    // only do this if the structure has not been initialized -- meaning
    // the pointers can be set once.
    if (NULL == VdmTib->PrinterInfo.prt_Status) {

        VdmTib->PrinterInfo.prt_PortAddr[0] = PortTable[0];
        VdmTib->PrinterInfo.prt_PortAddr[1] = PortTable[1];
        VdmTib->PrinterInfo.prt_PortAddr[2] = PortTable[2];

        VdmTib->PrinterInfo.prt_Handle[0] =
        VdmTib->PrinterInfo.prt_Handle[1] =
        VdmTib->PrinterInfo.prt_Handle[2] = NULL;

        // default mode is kernel simulating status port read
        // mode will be changed if
        // (1). A vdd is hooking printer ports.
        // (2). Dongle mode is detected
        VdmTib->PrinterInfo.prt_Mode[0] =
        VdmTib->PrinterInfo.prt_Mode[1] =
        VdmTib->PrinterInfo.prt_Mode[2] = PRT_MODE_SIMULATE_STATUS_PORT;

        // primarily for dongle
        VdmTib->PrinterInfo.prt_BytesInBuffer[0] =
        VdmTib->PrinterInfo.prt_BytesInBuffer[1] =
        VdmTib->PrinterInfo.prt_BytesInBuffer[2] = 0;

        // primarily for simulating printer status read in kernel
        VdmTib->PrinterInfo.prt_State = State;
        VdmTib->PrinterInfo.prt_Control = Control;
        VdmTib->PrinterInfo.prt_Status = Status;
        VdmTib->PrinterInfo.prt_HostState = HostState;

        //
        // Give the kernel printer emulation an opportunity to cache the
        // pointers
        //
        if (!NT_SUCCESS(NtVdmControl(VdmPrinterInitialize,NULL))) {
           return FALSE;
        }

        return TRUE;
    } else {
            return FALSE;
    }
}

BOOLEAN MonitorEnablePrinterDirectAccess(WORD adapter, HANDLE handle, BOOLEAN Enable)
{
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    ASSERT(VDM_NUMBER_OF_LPT > adapter);
    if (Enable) {
        // if the adapter has been allocated by a third party VDD,
        // can't do direct io.
        if (PRT_MODE_VDD_CONNECTED != VdmTib->PrinterInfo.prt_Mode[adapter]) {
            VdmTib->PrinterInfo.prt_Mode[adapter] = PRT_MODE_DIRECT_IO;
            VdmTib->PrinterInfo.prt_Handle[adapter] = handle;
            // NtVdmControl(VdmPrinterDirectIoOpen, &adapter);
            return TRUE;
        }
        else
            return FALSE;
    }
    else {
        // disabling direct i/o. reset it back to status port simulation
        if (VdmTib->PrinterInfo.prt_Handle[adapter] == handle) {
            NtVdmControl(VdmPrinterDirectIoClose, &adapter);
            VdmTib->PrinterInfo.prt_Mode[adapter] = PRT_MODE_SIMULATE_STATUS_PORT;
            VdmTib->PrinterInfo.prt_Handle[adapter] = NULL;
            VdmTib->PrinterInfo.prt_BytesInBuffer[adapter] = 0;
            return TRUE;
        }
        else
            return FALSE;
    }
}

BOOLEAN MonitorVddConnectPrinter(WORD Adapter, HANDLE hVdd, BOOLEAN Connect)
{
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;
    if (VDM_NUMBER_OF_LPT <= Adapter)
        return FALSE;
    if (Connect) {
        VdmTib->PrinterInfo.prt_Mode[Adapter] = PRT_MODE_VDD_CONNECTED;
        VdmTib->PrinterInfo.prt_Handle[Adapter] = hVdd;
        return TRUE;
    }
    else {
        if (hVdd == VdmTib->PrinterInfo.prt_Handle[Adapter]) {
            VdmTib->PrinterInfo.prt_Mode[Adapter] = PRT_MODE_SIMULATE_STATUS_PORT;
            VdmTib->PrinterInfo.prt_Handle[Adapter] = NULL;
            return TRUE;
        }
        else return FALSE;
    }
}

BOOLEAN MonitorPrinterWriteData(WORD Adapter, BYTE Value)
{
    USHORT BytesInBuffer;
    PVDM_TIB VdmTib;

    VdmTib = (PVDM_TIB)NtCurrentTeb()->Vdm;

    ASSERT(VDM_NUMBER_OF_LPT > Adapter);
    BytesInBuffer = VdmTib->PrinterInfo.prt_BytesInBuffer[Adapter];
    VdmTib->PrinterInfo.prt_Buffer[Adapter][BytesInBuffer] = Value;
    VdmTib->PrinterInfo.prt_BytesInBuffer[Adapter]++;

    return TRUE;
}

/*  CheckScreenSwitchRequest -
 *
 *  This function checks if timer thread has asked us to stop such that it
 *  can handle the fullscreen and windowed switch.
 *  If yes, we will signal that we are stopped and wait for resume event.
 *
 */
VOID CheckScreenSwitchRequest(HANDLE handle)
{
    DWORD status;

    //
    // Check if Suspen is requested.  If yes, we will signal that we are going to
    // the wait state and wait for the resume event
    // Since 'handle' event is a manual event, it is important that
    // we check-and-wait in a loop such that timer thread will not pick up the
    // 'handle' event between the wait-for-resume and the ResetEvent(handle).
    //
    while (TRUE) {
        status = WaitForSingleObject(hSuspend, 0);
        if (status == 0) {
            SetEvent(handle);
            WaitForSingleObject(hResume, INFINITE);
            ResetEvent(handle);
        } else {

            //
            // Make sure event is reset before leaving this function
            //
            ResetEvent(handle);
            return;
        }
    }
}